After three years in Berlin, he returned to Poland in 1840 to marry Aleksandra Müller. He got a job as an organist in Vilnius and also worked as a private piano tutor.[4] The Moniuszkos had ten children.

Around 1840, he began to compose strongly, writing his first operas and several other stage works, as well as sacred music and secular cantatas.[6]

During his lifetime Moniuszko traveled many times to St. Petersburg where his concerts were very well received.[2] He was the mentor of César Cui.

In 1848 in Vilnius, he staged and conducted the first performance of his opera Halka. After the triumph of his new four-act version of Halka at Warsaw on 1 January 1858, he toured France. It was soon later staged in Prague, Moscow and St. Petersburg,[3] where it met with great success.[7]

On 1 August 1858 he was made conductor of the Polish Opera in the Grand Theatre in Warsaw. In 1864, Moniuszko started lecturing at the Music Institute in Warsaw, where he also directed a choir. His disciples included, among others, Zygmunt Noskowski and Henryk Jarecki.[4]